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International Concrete Abstracts Portal

Showing 1-5 of 16 Abstracts search results

Document: 

SP142-14

Date: 

January 1, 1994

Author(s):

A. Samer Ezeldin

Publication:

Symposium Papers

Volume:

142

Abstract:

Partially prestressed beams contain both prestressed and non-prestressed reinforcement. Addition of steel fibers results in an increase in first crack moment and flexural strength and a decrease in deflection and reinforcement stresses. This paper presents an analytical method to compute the deformation of partially prestressed beams made with fiber reinforced concrete. A computer program was developed to evaluate the theoretical moment-curvature and moment-deflection relationships. It uses the linear and nonlinear stress-strain relationships of the composite materials. Strain compatibility concept is incorporated to obtain the stresses in concrete, prestressed steel, and non-prestressed steel. The cracking moment and the nominal flexural strength are also computed. The method can analyze prestressed sections of rectangular, T, I, and box shapes. The analytical predictions of the proposed method agree well with experimental results.

DOI:

10.14359/3964


Document: 

SP142-07

Date: 

January 1, 1994

Author(s):

H. Sakai, K. Takahashi, Y. Mitsui, T. Ando, M. Awata, and T. Hoshijima

Publication:

Symposium Papers

Volume:

142

Abstract:

Carbon fiber reinforced cement composite (CFRC) has outstanding advantages in its dynamic characteristics and durability. Among other characteristics, it has a flexural strength three to four times higher than that of ordinary concrete. Taking advantage of these characteristics of CFRC in designing curtain walls, the manufacturing of thin, lightweight curtain walls becomes possible. This paper describes experimental studies conducted using CFRC specimens to examine the effects of mixing and placing conditions upon the flexural strength of CFRC, scale effects, and the fatigue of CFRC subject to repetitive loads. Furthermore, based on the results of these experiments, allowable bending stress in designing curtain walls was determined and its authenticity verified by having a full-scale composite panel undergo a wind resistance test. Several examples of CFRC used as curtain walls are also introduced.

DOI:

10.14359/1184


Document: 

SP142-01

Date: 

January 1, 1994

Author(s):

S. P. Shah M. Sarigaphuti, and M. E. Karaguler

Publication:

Symposium Papers

Volume:

142

Abstract:

Concrete structures shrink when they are subjected to a drying environment. If this shrinkage is restrained, then tensile stresses develop and concrete may crack. One of the methods to reduce the adverse effects of shrinkage cracking is to reinforce concrete with short randomly distributed fibers. Another possible method is the use of wire mesh. The efficiency of fibers and wire mesh to arrest cracks in cementitious composites was studied. Different types of fibers (steel, polypropylene, and cellulose) with fiber content of 0.25 and 0.5 percent by volume of concrete were examined. Ring-type specimens were used for restrained shrinkage cracking tests. These fibers and wire mesh show significant reduction in crack width. Steel fiber reinforced concrete (0.5 percent addition) showed 80 percent reduction in maximum crack width and up to 90 percent reduction in average crack width. Concrete reinforced with 0.5 percent polypropylene or cellulose fibers was as effective as 0.25 percent steel fibers or wire mesh reinforced concrete (about 70 percent reduction in maximum and average crack width). Other properties, such as free (unrestrained) shrinkage and compressive strength were also investigated.

DOI:

10.14359/1178


Document: 

SP142-06

Date: 

January 1, 1994

Author(s):

Nemkumar Banthia

Publication:

Symposium Papers

Volume:

142

Abstract:

Describes improvements in the performance characteristics of cements due to carbon fiber reinforcement. In particular, the structure, physical properties, mechanical behavior, and durability aspects of carbon-cement composites using pitch-based fibers are discussed. The various possible applications of these composites in structural and nonstructural applications are enumerated and future research needs to be identified.

DOI:

10.14359/1183


Document: 

SP142-13

Date: 

January 1, 1994

Author(s):

D. J. Stevens and D. Liu

Publication:

Symposium Papers

Volume:

142

Abstract:

It is well recognized that fiber reinforced concrete (FRC) exhibits a number of superior properties relative to plain concrete, such as improved strength, ductility, impact resistance, and failure toughness. These advantageous features of FRC can lead to novel structural applications, for which standard design and analysis procedures must be supplemented by numerical modeling (for example, the finite element method). This, in turn, makes necessary the development of satisfactory constitutive models that can predict the behavior of FRC under different load conditions, both monotonic and cyclic. In this paper, a constitutive model for FRC is developed loosely within the theory of mixtures. For plain concrete, an anisotropic, strain-based, continuum damage/plasticity model with kinematic and isotropic damage surfaces is developed. To represent the effect of the fibers, a simplified model that accounts for the tensile resistance of the fibers and the enhanced tensile resistance of the plain concrete is proposed. The predictions of the FRC constitutive model are compared to data from laboratory tests of steel fiber reinforced concrete (SFRC) specimens under uniaxial and biaxial loadings.

DOI:

10.14359/3963


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